It is very simple to identify the severely malnourished patient by current body composition analysis techniques. However, identification of early malnutrition is difficult. The study of muscle function as an indicator of malnutrition was chosen due to the obvious effects of muscle wasting seen during prolonged malnutrition. In patients with malnutrition, changes in muscle contractility, relaxation rate and endurance (muscle function) may precede the detectable changes in body composition. The available evidence suggests that malnutrition may alter muscle function by altering the ability of the muscle to regulate the calcium content of the muscle fiber.
Moxhan has demonstrated the similarity of muscle function between various groups of muscles including the sternocleidomastoid, quadriceps, adductor pollicis and diaphragm. This similarity was seen when results were normalized by the maximal force obtained from each group. "Contractile properties and fatigue of the diaphragm in man", Moxham et al., THORAX 36:164-168 (1981). Therefore it can be postulated that the adductor pollicis muscle function represents muscle function as a whole. Function of the adductor pollicis muscle can be assessed by electrical stimulation of the ulnar nerve. It has been shown by various investigators that the maximal relaxation rate in malnourished individuals differs significantly from normal controls.
The present invention provides an apparatus and method which may be employed for assessing muscle function as an indication of the nutritional status of a person.